SY/T 0522-1993 Determination of wax precipitation point of crude oil by rotational viscometer method SY/T0522-1993 Standard download decompression password: www.bzxz.net

Petroleum and Natural Gas Industry Standard of the People's Republic of China SY/T 0522—93
Determination of Wax Point of Crude Oil
Rotational Viscometer Method
Published on March 27, 1993
Ministry of Energy of the People's Republic of China
Implementation on September 1, 1993
1 Subject Content and Scope of Application
Petroleum and Natural Gas Industry Standard of the People's Republic of China Determination of Wax Point of Crude Oil Rotational Viscometer Method
This standard specifies the method for determining the wax point of crude oil using a rotational viscometer. This standard is applicable to the determination of the wax point of crude oil with a wax content of more than 5% and a water content of less than 0.5%. 2 Reference standards
GB2538 Crude oil test method
GB4756 Sampling method for petroleum and liquid petroleum products GB8170 Numerical rounding rules
3 Method overview
SY/T D522-93
The sample is heated in the condensation viscometer measurement system until the solid wax therein is converted into liquid, and then cooled at a specified rate. At the same time, the rotation viscometer is started to measure and record the corresponding values ​​of shear stress (torque) and temperature at a fixed shear rate, and a typical curve is drawn. When the temperature drops to a certain value, wax precipitates from the homogeneous liquid, causing the curve to begin to turn. The temperature corresponding to this point can be regarded as the wax precipitation point of the sample.
4 Instruments
4.1 Rotation viscometer
4.1.1 It has the function of continuously measuring shear stress at a fixed shear rate. 4.1.2 Shear rate range 1~1000s-.
4.1.3 Instrument reproducibility is not more than ±2%.
4.2 Constant temperature circulator
Constant temperature range 0100℃, temperature fluctuation does not exceed 0.1℃. 4.3 Thermometer
Digital display or glass mercury thermometer, graduation value 0.1. 4.4 xy recorder
Record shear stress-temperature (time) curve. 5 Sample
Obtain samples according to GB4756, and determine that the water content of the sample is below 0.5%. If the water content exceeds 0.5%, it is necessary to dehydrate according to GB2538 to meet the requirements.
6 Test steps
6.1 Place the viscometer containing about 150g of sample in a warm water bath and stir the sample to make it uniform. Load the sample according to the requirements of the rotational viscometer measurement system.
Approved by the Ministry of Energy of the People's Republic of China on March 27, 1993, and implemented on September 1, 1993
$Y/T 0522-93
6.2 Connect the thermocirculator and the rotational viscometer to the system, and raise the temperature of the system and the sample to 70℃, and the rough flow rate is 10i. If the sample's humidification point can be estimated, it can also be raised to 15-25 above the humidification point.) 6.3 Control the thermocirculator to continuously dehumidify at a rate of 0.2-1G/mi1, and start the rotational viscometer at the same time, so that it operates at a fixed value within the 10-600-1 frequency range. Record the corresponding position of the force (torque) and temperature at 64 seconds to give the test curve. Until the temperature drops to a point where the slope does not change significantly, continue to measure ~7 points. 7 Measurement results
1. Redraw the test curve to a flat logarithmic scale (see Appendix A Figure A.1 for more details). The number of data points taken should not be less than 1, and the number of data points at the two test curve change points should be roughly equal. Connect the high and low temperature points of the data points into a straight line. When the slope of the line connecting the base point and the subsequent points changes significantly, the temperature corresponding to the point is the test temperature of the sample. 2. Or input the corresponding values ​​of the test measurement into the computer according to the regression calculation program (see the example in the recording). The data should not be less than 1, and the two test data points are roughly equal: use a computer to identify the point where the slope of the test line changes. From a certain point, the regression line of the subsequent points deviates significantly from the regression line of the high temperature section. Take the starting point of the test group corresponding to the intersection of the two points. Density
8.1 Repeatability
When the same operator uses the same instrument in the same test year and follows the specified steps of the method, the difference between the two results shall not exceed 2°C when the same sample is tested repeatedly at consecutive times. 9 Density Www.bzxZ.net
The arithmetic mean of the two repeated test results, rounded to the nearest digit according to 8170, is the wax precipitation point of the sample and the result is reported.
SY/T 0522—93
Appendix A
Test curve and redrawn curve for determination of wax precipitation point (reference)
Yideng+
SY/T 0522—93
Analysis of Dayi
Fresh original instant milk
Warm shear ingot
This program is written in BASIC language
Program instructions
Main special symbols used in the program
STRESS
B2.2 Method of inputting data
SY/T 0522--93
Appendix B
Calculation program for determining wax precipitation point
(reference)
Number of test temperature points
Shear stress (torque) recorded in the test
Logarithm of shear stress (torque)
Temperature value corresponding to STRFSS
Sum of square difference between regression value and measured stress (torque) value Slope of regression line in high temperature section
Slope of assumed straight line
Regression line distance in high temperature section
Regression line distance in low temperature section
The minimum sum of square deviations of regression line between each measured value in high and low temperature sections is determined, that is, the wax precipitation point is determined. According to the prompts on the display screen, enter the corresponding values ​​of each set of temperature and shear stress (torque) in sequence. .B2.3 Program running
Run the program in BASIC mode. First, enter the number of temperature points (N), press Enter, and enter all data according to B.2.2. You must press Enter after entering each set of data. The screen will display the temperature points selected by the computer to form the high-temperature regression line and the calculated wax precipitation point temperature.
B3 Program List
I0 INPUT\N-\ N
20 DIM STRESS(N), S(V), T(N), W(20). K(20), G(20), Y(20), Z(20)30 FOR I=1 TO N
4D PRINT\TEMPERATURE('I')\;\STRESS(I;\)\50 INPUT T(I). STRESS()
60 S(I)=LOG(STRESS(D)
70 NEXTI
80 L=0
90 FOR I-2 TO N-2
100 L=L+1
110 CP=0 : DP-0 EP=0 -FP=0
120 FOR J=1 TO 1
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130 CP=CP+T(J) ^ 2 1 DP=DP+S(I) : EP=EP+S(J) T(D) : FP-FP+T(J)140 NEXT J
150 K(L)-(DP * FP-1 * EP)/(FP ~ 2-I +CP)16D Y(L)=(EP FP--CP DP)/(FP ^2--I * CP)170 W(L)=0
180 FOR J=1TO1
190 W(L)= W(L)+(S(J)-K(L) T()-Y(L)) - 2200 NEXT J
210 CP=0 : DP=0 : EP=D : FP=0220 FOR J=I+1 TO N
230 CP=CP+T(J)2:DP=DP+S(J):EP=EP+S(J) *T(J):FP=FP+T(J)240 NEXT 1
250 QN-[
260 G(L)-(P* FP)-Q *EP)/(FP\2-Q+CP)270 Z(L)-(EP * FP-CP + DP)/(FP\ 2--Q *CP)280 0R J=I+1 TO N
290 W(L)- W(1.)+(S(J)-G(1.) + T()-Z(L)) ~ 2300 NEXT J
310 NEXT I
320 S=0
330 FOR J-2 TO L
340 1F W(1)
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